On 08/10/2021 03:59, Ian Rogers wrote:

On Thu, Oct 7, 2021 at 5:03 PM Andi Kleen [off-list ref] wrote:

quoted

On 10/6/2021 9:26 AM, John Garry wrote:

quoted

On 06/10/2021 09:43, James Clark wrote:

+ Andi

quoted

On 05/10/2021 11:10, John Garry wrote:

quoted

On 04/10/2021 17:00, Andrew Kilroy wrote:

quoted

There are some syntactical mistakes in the json files for the
Cortex A76
N1 (Neoverse N1).  This was obstructing parsing from an external tool.

If the trailing comma is not allowed by standard, then maybe we
should fix our parsing tool to not allow it also. However maybe
there is a good reason why we allow it..

It would be nice to do, because I have also made similar fixes
before. We looked at the STRICT option
in the parser (https://github.com/zserge/jsmn), but even then it
seems to allow trailing commas.

Trailing commas are not allowed in the json standard, but there is a
split between parsers
where some allow it and others don't. Specifically the Python parser
doesn't allow it, and Python
can easily be involved in some workflow that parses these files.

The only way forwards I can think of is either getting a change
accepted upstream to the parser
and then updating it in perf, switching to a different parser, or
doing some hack to add an extra
step in perf to look for commas. None of which sound ideal.

Looking at the license in jsmn.c, we seem to be ok to modify it (to
error on non-standard trailing ',') - that parser has already
apparently been modified in mainline.

If we do that then I hope that there are not to many violations in out
JSONs, including downstream.

Sure we can modify the file. I already did some minor changes when I
submitted it originally.

-Andi

jsmn is a somewhat frustrating way to work on json code and working on
a forked version of jsmn was frustrating in [1]. Could we assume
python on build systems and rewrite jevents in python?

Seems reasonable to me, although maybe a big job. I suppose there could be
an empty generated pmu file for systems that don't have Python and only the
ones listed in pmu-events/arch/ would need it.

James

Thanks,
Ian

[1] https://lore.kernel.org/lkml/20201110100346.2527031-1-irogers@google.com/ (local)

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